John chapter 6 is an excellent attempt on the part of Jesus to lead His disciples to think beyond the earthly, to forge in them a character that thinks of heavenly things, because they had to be clear that their citizenship was not earthly.
35 And Jesus said unto them, I am the bread of life: he that cometh to me shall never hunger; and he that believeth on me shall never thirst.
36 But I said unto you, That ye also have seen me, and believe not.
37 All that the Father giveth me shall come to me; and him that cometh to me I will in no wise cast out.
38 For I came down from heaven, not to do mine own will, but the will of him that sent me.
John 6:35-38 (KJV)
Before Jesus told His disciples that He was the bread of life, He made reference to how God fed the people of Israel with manna from heaven, however, it is logical that they were not satisfied with this bread, since it was earthly.